Method of storing and concentrating anhydrous hydrogen chloride



1944- s. e. OSBORNE ET AL 2,356,345

METHODS OF STORING AND CONCENTRATING ANHYDROUS HYDROGEN CHLORIDE Filed Dec. 18, 1941 -3ME kc 1 \iqqfiqw g em ow cw 3 cm Q sk kswwzs 8 quuigkc 55mg? INVENTOR BY mi.

t/ I ATTORNEY L Patented Aug. 22 1 944 UNITED [STATES PATENT OFFICE METHOD OF STORING AND CONCENTRAT- ANI IYDROUS HYDROGEN CHLORIDE Sidney G. Osborne, St. Davids, Ontario, Canada,

and Aylmer H. Maude, Niagara Falls, N. Y., asslgnors to Hooker Electrochemical Company, Niagara Falls, N. Y., a corporation of New York Application December 18, 1941, Serial P11423446 1 Claim. (c1. 23-154) It is known that certain materials form addit."-n compounds with anhydrous hydrogen chloride and that the hydrogen chloride may be subsequently recovered for use as required by application of heat to the compound. Among the materials known to form suchaddition compounds are certain salts of heavy metals,,such as cupric chloride, copper, lead, cadmium, silver, mercury, tin, bismuth, and antimony sulphate, phosphate, phosphite and hypophosphite. and thallium and ferric phosphate Many of these salts areheavy or expensive or give off the HCl at an inconveniently high temperature, Copper, lead and stannous sulphates form the stable addition compounds CuS04.2HCl, P bS04.2HCl and SnSO4.1.5HCl. The temperatures at which these compounds begin to give off the HCl depend upon the degree of saturation, but at." atmospheric pressure, and in an atmosphere of H01, they will be found to have given ofi most of the HCl at 130? C. These salts are therefore at present among the preferred salts for our purpose.

However, these salts, when dehyrated, are generally. powdery and hygroscopic. The carrying out. of the absorption and desorption therefore involvesv considerable diificulty. In U. S. Patent No. 2,234,738 there is described a method and apparatus for. overcoming this difliculty, which comprises impregnating inert porous granular or plastic material with an aqueous solution of the salt and then driving ad the water so as to leave the salt distributed. throughout the \material.

at a temperature leaving it in powdery form and used by it'self, without any inert porous supportin material.

In the patent it is stated that the gas is forced into the pores of the porous material, thus implying that it is supplied under pressure. However, the pressure is only that corresponding to the resistance of the solid block of absorptive stantial pressure, especially when the absorptive .The material thus impregnated is enclosed in an air tight container, thus excluding moisture. In the patent, the materials mentioned are .Alfrax, Alundum," pumice and clay, These materials are largely composed of aluminum oxide or silimaterial is of a loose, powdery or granular nature, permitting the gas to contact it everywhere at substantially the same pressure. If the gas is dilute the hydrogen chloride is selectively absorbed out of the mixture and the pressure is maintained by controlling the escape of the diluent gases at the exit. By means of the Nash Hydroturbine, a rotary device which compresses gases bymeans of a liquid piston, such as concentrated sulphuric acid, it is practicable to compress hydrogen chloride up to a'pressure of about 35 lbs. per sq. in. At 30 lbs. perv sq. in. the rate of absorption of the gas is multiplied several times. Moreover, thecompleteness of absorption is increased at the same time; that is to say,

- in the exit gas is reduced, for a given rate of cate. In co-pending application Serial No. 423.-

444, filed simultaneously herewith, there is disclosed an inert porous material stated to be of uperior resistance to the action of anhydrous hydrogen chloride over long periods of use; namely infusorial earth, This contains very little aluminum and is largely silicon dioxide. It may be impregnated with the-salt as a powder and remain in powdered form afterward, or it may be compacted by means of a binder, preferably sodium silicate,'dried, crushed and gran.- ulated, and then impregnated. with the salt. In copending application Serial No. 423,445 filed simultaneously herewith there is disclosed a container in which the absorptive material may be.

- charging at atmospheric pressure.

charging, as compared with the percentage when The efiect of charging under pressure is illustrated in the graphs, in which percentage of HCl in the exit gas is plotted against percentage of theoretical saturation, when charging HCl gas of a concentration of per cent by volume (the balancebeing air), at room. temperature into an absorptive 'mass consisting of infusorial earth, in granular form, impregnated with copper sulphate. From this graph it willbe seen that when charging at'atmospheric pressure at the'rate of i lb. of 1501 per hour per cubic foot of absorptive mass, at ,75 per cent. of theoretical saturation,

' which is the practicallimit/the exit'gas contains used in powdered form, and for this purpose the salt .may be used by impregnating powdered 35 per cent HCl. When charging under a pressure of 30 lbs. gauge, on the other hand, and at the rated 2 lbs. of 1101 per hour per cubic foot or mass, or twice the previous ehargmgrate, at 75 per cent of saturation the exit gas contains 12% percentHCl. Thisdoesnotmelnthatthe absorptive mas can be charged at pressure atthe rate of lib. of HCl per hour per cubic foot. Under these conditions the mean H01 content of the exit gases from start to 75 per cent saturation would be about 20 per cent. Thlsistoomuchficltobeallowedmgotowaste. At atmosfih 'c pressure the highest economical charging 111' is therefore about A lb. perhour per cubic foot of mass. Neither does the graph mean that when charging under 30 lbs. pressure at the rate of 2 Ibs HCl per hour per-cubic foot of mass the exit gas contains 12% per cent HCl throughout the operation. As a matter of fact, the mean HCl content of the exit gas under .these conditions is only about 4.7 per cent. This quanas 10 lbs. gauge, a very, useful gain in charging rate may be realized, This is or grant m tanceastherateotchargingddumlneshea pacit! of a given installation for M.

' not more than 2 pounds of hydrogen chloride per hour per cubic foot of mass, until the mass has absorbed hydrogen chloride up to 75 per cent of its ultimate capacity. and subsequently hectlng the mass m re-evolve concentrated hydrogen chloride therefrom,

HEY G. OSBORNE.

AYLHER H. MAUDE. 

